The objectives of the proposed work are to increase the sensitivity of the beta subunit radioimmunoassay for human chorionic gonadotropin in order to further examine its usefulness as a biochemical marker for neoplasia, and to determine the specificity of human chorionic gonadotropin as a tumor-associated antigen in the non-pregnant state. The sensitivity of the method will be increased by adsorption of hCG from blood samples onto Concanavalin-A, elution and concentration, followed by measurement with an improved antiserum drected towards the beta subunit of hCG. The specificity of the assay will also be increased by the generation of new antisera to the native beta subunit, as well as modified forms of the beta subunit of hCG. Studies will also be carried out on the hCG-like glycoprotein present in the normal human testes, and further purification and characterization of this material will be accomplished. Finally, a prospective evaluation of the value of hCG measurments for the immunodiagnosis of cancer and for following the effects of therapy will be made by comparing patients whose tumors produce hCG or its subunits to those whose tumors do not, in regard to clinical presentation, duration of disease, duration and extent of disease, age, sex, race, tumor histology and grade, response to therapy, known areas of metastases, and survival. BIBLIOGRAPHIC REFERENCES: Braunstein, G.D., Rasor, J., and Wade, M.E., Presence in Normal Human Testes of a Chorionic-Gonadotropin-Like Substance Distinct from Human Luteinizing Hormone, N. Engl. J. Med., 293:1339-1343, 1975.